I looked at a cheap "sport bag" at Sportsman's Warehouse. I did sling it over my shoulder, and it gave me an idea of what it would be like walking and shooting with it on.
While I don't think I'd ever buy it, it did have some nice features: a nice top flap with a zippered mesh pocket, two full width compartments, the narrower of the two has 6-mesh pockets, and another zippered full width sleeve.
On both ends, there are zippered pocket.
I wish it was it bit better quality. At $25, maybe I should take a chance wiith it. Could always use it as a template for a home brew haversack.